Study on pollution characteristics of carbonaceous aerosols in Xi'an city during the spring festival

The samples of PM_2.5 with 8 times periods were collected using Automated Cartridge Collection Unit (ACCU) of Rupprecht& Patashnick (R&P)Corporation, and monitored by R&P1400a instrument of TEOM series online during 2011 Spring Festival in Xi'an city. The organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and water-insoluble organic carbon (WIOC) contents of 3 h integrated PM_2.5 were analyzed to evaluate the influence of firework display on the carbonaceous components in urban air. The mass concentration of PM_2.5 was found increased significantly from 00: 00 A.M. to 02: 59 A.M. at the Chinese Lunar New Year's Eve than the non-firework periods, reaching 1 514.8 μg·m^-3 at 01: 00 A.M. The mass concentrations of OC, EC, WSOC, and WIOC during the same time period were 123.3 μg·m^-3, 18.6 μg·m^-3, 66.7 μg·m^-3, and 56.6 μg·m^-3, about 1.7, 1.2, 1.4, and 2.2 times higher than the average in normal days, respectively. Correlation analysis among WSOC, OC, and EC contents in PM_2.5 showed that firework emission was an obvious source of carbonaceous aerosol in the Spring Festival vacation. However, it only contributes to 9.4% for aerosol in fireworks emission.